1. Field of the Invention
This invention pertains to the field of metal-gas batteries, such as nickel-hydrogen batteries. Such batteries exhibit high specific energy and find particular applicability in spacecraft, where weight savings is critical.
2. Description of the Prior Art
A prior art search uncovered the following U.S. patent references:
U.S. Pat. No. 4,115,630 is illustrative of the prior art. The present invention differs from this patent in that: the electrical function of the center rods is eliminated; much shorter and lighter terminal leads are used; the end plates and center rod do not attach rigidly to the weld ring of the pressure vessel, thus the pressure vessel can expand independently of the electrode stacks; and the weld ring does not attach to the battery stack.
U.S. Pat. No. 4,177,328 discloses a wall wick used in a nickel-hydrogen cell. The present invention addresses an improvement in the structural/mechanical design and does not intend to provide an electrolyte management device, such as the wall wick. The present invention can be combined with a wall wick or an insulative barrier to prevent electrolyte-pressure vessel interaction.
U.S. Pat. No. 3,669,744 discloses a hermetically sealed nickel-hydrogen storage cell; an end plate bonded to the inner wall of the pressure vessel supports the battery stack; one of the terminals is fed through the upper end of the pressure vessel along the center axis of the vessel. Since the electrode stack is supported only by the bus bars, mechanical loading and vibration could cause electrode fracture and a resulting cell capacity loss. The present invention avoids this problem by providing axial stack support via the center rod and radial support via the end plates with a flexible joint between terminals and bus bars.
U.S. Pat. No. 3,867,199 discloses a type of electrode that could be utilized in the present invention.